Ester alcohols, in particular, ester polyols are very useful for the production of polyurethane-based coatings and foams, polyester applications, and lubricants. The present invention provides a process using renewable resources, such as, oils and fats, fatty acids, and fatty acid esters derived from plants and animals to produce polyurethane foams, coatings and lubricants. Chemicals derived from plants and animal fats are oleochemicals. Oleochemicals are analogous to petrochemicals, which are chemicals derived from petroleum. As the price in crude oil increases, there will be an increased demand for oleochemical-based substances.
Polyols are a class of alcohols having at least two or more hydroxyl groups. An ester is a compound derived by reacting carboxylic acids with a hydroxyl-containing compounds such as alcohols or phenols. Esters involved in the current invention are formed by condensing an acid with an alcohol.
One class of biobased lubricants are polyol esters which are formed by full esterification of all available hydroxyl groups of a polyol with fatty acids. For example, the polyol ester trimethylolpropane (TMP) trioleate, is prepared by the esterification of the polyol TMP with various grades of oleic acid. TMP trioleate contains the unsaturated oleic acid that provides lower pour points compared to the typical long chain saturated fatty acid esters. TMP trioleate is a common biobased lubricant currently available on the market.
Ester polyols are a class of compounds consisting of internal ester groups and pendant hydroxyl groups that are provided by primary polyols (a compound containing two or more hydroxyl groups). Ester polyols and their preparation are described in WO2007027223 and WO20102012078505. One of the disadvantages of some of the ester polyols used in lubricants is that their crystallization temperature is relatively high. Ester polyols prepared from feedstock with high amounts of saturated fatty acids (e.g. palmitic, stearic) may undergo phase separation, leading to two or more phases which are difficult to process into useful products.
Accordingly, there still is a need in this technical field for improved methods for the preparation of ester polyols.